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Implementation of neural networks to frontal electroencephalography for the ide...

Ferreira, Ana Isabel Leitão; Vide, Sérgio; Nunes, Catarina S.; Neto, Joaquim; Amorim, Pedro; Mendes, Joaquim

Objective: General anesthesia is a reversible drug-induced state of altered arousal characterized by loss of responsiveness (LOR) due to brainstem inactivation. Precise identification of the LOR during the induction of general anesthesia is extremely important to provide personalized information on anesthetic requirements and could help maintain an adequate level of anesthesia throughout surgery, ensuring safe ...


Electromyographic assessment of blink reflex throughout the transition from res...

Ferreira, Ana Isabel Leitão; Vide, Sérgio; Felgueiras, João; Cardoso, Márcio; Nunes, Catarina S.; Mendes, Joaquim; Amorim, Pedro

General anesthesia is a reversible drug-induced state of altered arousal characterized by loss of responsiveness due to brainstem inactivation. Precise identification of the moment in which responsiveness is lost during the induction of general anesthesia is extremely important to provide information regarding an individual's anesthetic requirements and help intraoperative drug titration. To characterize the tr...


Patterns of hysteresis between induction and emergence of neuroanesthesia are p...

Ferreira, Ana Isabel Leitão; Correia, Rui; Vide, Sérgio; Ferreira, Ana Dias; Kelz, Max B.; Mendes, Joaquim; Nunes, Catarina S.; Amorim, Pedro

Recovery of consciousness is usually seen as a passive process, with emergence from anesthesia depicted as the inverse process of induction resulting from the elimination of anesthetic drugs from their central nervous system sites of action. However, that need not be the case. Recently it has been argued that we might encounter hysteresis to changes in the state of consciousness, known as neural inertia. This p...


Usefulness of the blink reflex to assess the effect of propofol during inductio...

Ferreira, Ana Isabel Leitão; Nunes, Catarina S.; Mendes, Joaquim; Amorim, Pedro

The aim of this study was to investigate the relation between the blink reflex evoked by an electrical stimulus and the depth of anesthesia induced with intravenous anesthetic drug propofol. The blink reflex was stimulated before the propofol infusion started (baseline) and after, every 6 s. The electromyographic responses and the level of sedation/anesthesia scores as well as the estimated effect-site concentr...


Performance of blink reflex in patients during anesthesia induction with propof...

Ferreira, Ana Isabel Leitão; Vide, Sérgio; Felgueiras, João; Cardoso, Márcio; Amorim, Pedro; Mendes, Joaquim; Nunes, Catarina S.

The amount of propofol needed to induce loss of responsiveness varied widely among patients, and they usually required less than the initial dose recommended by the drug package inserts. Identifying precisely the moment of loss of responsiveness will determine the amount of propofol each patient needs. Currently, methods to decide the exact moment of loss of responsiveness are based on subjective analysis, and ...


[Evaluation of Bispectral Index time delay in response to anesthesia induction:...

Ferreira, Ana Isabel Leitão; Mendes, Joaquim Gabriel; Nunes, Catarina Sofia; Amorim, Pedro

Background and objectives: According to the manufacturer, the Bispectral Index (BIS) has a processing time delay of 5-10s. Studies addressing this have suggested longer delays. We evaluated the time delay in the Bispectral Index response. Methods: Based on clinical data from 45 patients, using the difference between the predicted and the real BIS, calculated during a fixed 3minutes period after the moment the B...


Do we have today a reliable method to detect the moment of loss of consciousnes...

Ferreira, Ana Isabel Leitão; Nunes, Catarina S.; Mendes, Joaquim; Amorim, Pedro

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control, including preventing intraoperative awareness episodes and overd...


EEG signatures at the transition between conscious and unconscious state during...

Ferreira, Ana Isabel Leitão; Mendes, Joaquim; Amorim, Pedro; Nunes, Catarina S.

The precise identification of the moment of Loss Of Consciousness (LOC) during the induction phase of general anesthesia is of extreme importance for the individualization of drug doses. In the lack of an objective method to assess this moment, the development of a new methodology is needed. In this observational study, Electroencephalogram (EEG) signatures that were associated with the moment of LOC are examin...


Neuro-fuzzy models to predict the required propofol amount for loss of consciou...

Ferreira, Ana Isabel Leitão; Mendes, Joaquim; Amorim, Pedro; Nunes, Catarina S.

This study presents several models to predict the total amount of the anesthetic drug propofol required to achieve loss of consciousness during the induction phase of anesthesia, considering different clinical variables. The data from 49 patients under anesthesia for neurosurgical procedures, were used in this study. Takagi-Sugeno-Kang (TSK) fuzzy models were used to describe the effect of clinical variables on...


Individualized anesthesia: independent predictive factors for the propofol indu...

Nunes, Catarina S.; Ferreira, Ana Isabel Leitão; Correia, Rui P.; Amorim, Pedro


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